1. Field of the Invention
This invention relates generally to apparatus for cleaning tubes in heat exchangers, and the like, and more particularly to apparatus whereby the effectiveness of the cleaning procedure can be readily determined during the procedure.
2. Description of the Prior Art
To function at top efficiency, every tube-type heat exchanger device, whether in a hot water or steam boiler or condenser, or an exchanger for heating or cooling a liquid or gas, requires that the surface of the tubes be clean and scale-free. The formation of mud deposits, or hard or soft scale on the heat transfer surface of the tubes can drastically reduce the flow or heat exchange through the tube walls. Such formations, which may typically occur on the interior wall of the tube may consist of silicates, sulphates, sulphites, carbonates, organic growths or other formations. Some such fouling agents can be corrosive to the tube material. In addition to the detrimental effect from heat transfer inhibition, and possible corrosion of tube material, the accumulation of scale on the inner wall of a tube decreases the area for fluid flow through the tube, and thus interferes with the flow. Accordingly it is desirable to maintain scale-free heat transfer surfaces.
Basically there are two types of mechanical tube cleaning devices, they being the internal type and external type. The internal type is one wherein both the drive motor and the cleaning tool enter the tube. This type is generally used for cleaning straight or curved tubes of large diameters. The external type is one which has the drive motor external to the tube and it drives a cleaning tool by means of a length of rigid hollow shafting or flexible shafting. This type is used for cleaning the small straight tubes found in condensers and heat exchangers used in the refrigeration and air-conditioning industries. Examples of the external drive type are found in U.S. Pat. Nos. as follows:
2,057,852--Nielsen--Oct. 20, 1936 PA0 2,090,174--Albright--Aug. 17, 1937 PA0 2,559,077--Sturgis--June 3, 1952
The patents identified above disclose devices which are merely examples, and this is by no means all of the devices which have ever been patented or produced for tube cleaning with a tool driven by drive means external to the tube.
One of the problems with the tube cleaning apparatus heretofore known is the fact that it is difficult to determine how well a tube is being cleaned, and how clean the tube is. The reason for this is the very long length of some tubes, and the fact that the end opposite that entered by the tube cleaning tool, is not open to light. Therefore, one has difficulty getting a good perception of how well the tool is cleaning the tube, or how well it has been cleaned, once the tool has been withdrawn. The present invention is intended to assist the workmen in overcoming these problems.